NAME¶
Dpkg::IPC - helper functions for IPC
DESCRIPTION¶
Dpkg::IPC offers helper functions to allow you to execute other programs in an
easy, yet flexible way, while hiding all the gory details of IPC
(Inter-Process Communication) from you.
METHODS¶
- spawn
- Creates a child process and executes another program in it.
The arguments are interpreted as a hash of options, specifying how to
handle the in and output of the program to execute. Returns the pid of the
child process (unless the wait_child option was given).
Any error will cause the function to exit with one of the
Dpkg::ErrorHandling functions.
Options:
- exec
- Can be either a scalar, i.e. the name of the program to be
executed, or an array reference, i.e. the name of the program plus
additional arguments. Note that the program will never be executed via the
shell, so you can't specify additional arguments in the scalar string and
you can't use any shell facilities like globbing.
Mandatory Option.
- from_file, to_file, error_to_file
- Filename as scalar. Standard input/output/error of the
child process will be redirected to the file specified.
- from_handle, to_handle, error_to_handle
- Filehandle. Standard input/output/error of the child
process will be dup'ed from the handle.
- from_pipe, to_pipe, error_to_pipe
- Scalar reference or object based on IO::Handle. A pipe will
be opened for each of the two options and either the reading
("to_pipe" and "error_to_pipe") or the writing end
("from_pipe") will be returned in the referenced scalar.
Standard input/output/error of the child process will be dup'ed to the
other ends of the pipes.
- from_string, to_string, error_to_string
- Scalar reference. Standard input/output/error of the child
process will be redirected to the string given as reference. Note that it
wouldn't be strictly necessary to use a scalar reference for
"from_string", as the string is not modified in any way. This
was chosen only for reasons of symmetry with "to_string" and
"error_to_string". "to_string" and
"error_to_string" imply the "wait_child" option.
- wait_child
- Scalar. If containing a true value, wait_child()
will be called before returning. The return value will of spawn()
will be a true value, but not the pid.
- nocheck
- Scalar. Option of the wait_child() call.
- timeout
- Scalar. Option of the wait_child() call.
- chdir
- Scalar. The child process will chdir in the indicated
directory before calling exec.
- env
- Hash reference. The child process will populate %ENV with
the items of the hash before calling exec. This allows exporting
environment variables.
- delete_env
- Array reference. The child process will remove all
environment variables listed in the array before calling exec.
- wait_child
- Takes as first argument the pid of the process to wait for.
Remaining arguments are taken as a hash of options. Returns nothing. Fails
if the child has been ended by a signal or if it exited non-zero.
Options:
- cmdline
- String to identify the child process in error messages.
Defaults to "child process".
- nocheck
- If true do not check the return status of the child (and
thus do not fail it it has been killed or if it exited with a non-zero
return code).
- timeout
- Set a maximum time to wait for the process, after that fail
with an error message.
AUTHORS¶
Written by Raphaël Hertzog <hertzog@debian.org> and Frank Lichtenheld
<djpig@debian.org>.
SEE ALSO¶
Dpkg, Dpkg::ErrorHandling